CCNA Labskill 4

In this activity, you will play the role of an onsite installation and support technician from an ISP. A customer has called the ISP complaining of e-mail problems and occasional poor Internet performance. On an earlier site visit, the technician had created diagram of the customer’s existing network shown here. The ISP is preparing a design for a network upgrade. The interim topology diagram for the proposed network is shown below. There is still a requirement for an IP addressing plan. One of the ISP network designers has made some notes on a simplified sketch of the proposed network, and has written some requirements. The designer asks you to create an IP address plan for the network upgrade.

Step 1: Analyze the network

a. Referring to the Rough Design Notes, determine the minimum number of hosts that a subnet needs to support the new network design.

For example: If four subnets are required and the largest subnet has to support 128 hosts, this is a problem, because a subnet in a class C network that has been partitioned four ways can support only 62 hosts.

d. Fill in the blanks to summarize the subnetting requirements of this new network design:

This network requires 129-256 subnets, each supporting 29 hosts. Therefore, 255.255.255.0/24 host ID bits are reserved for the subnet ID. With those values, this network supports subnets 8, each subnet having 254 hosts.

Step 2: Calculate the custom subnet mask

Now that the number of subnet ID bits is known, the subnet mask can be calculated. A class C network has a default subnet mask of 24 bits, or 255.255.255.0. What will the custom subnet mask be? The custom subnet mask for this network will be 255.255.255.128 or /25.

Step 3: Specify the host IP addresses

Now that the subnet mask is identified, the network addressing scheme can be created. The addressing scheme includes the subnet number, the subnet broadcast address, and the range of IP addresses assignable to hosts.

Complete the table showing all the possible subnets for the 192.168.1.0 network.

Subnet

Subnet Address

Host IP Address Range

Broadcast Address

8

255.255.255.0/24

192.168.1.1

255.255.255.129-255.255.255.135

8

255.255.255.0/24

192.168.1.2

255.255.255.136-255.255.255.144

8

255.255.255.0/24

192.168.1.3

255.255.255.145-255.255.255.53

8

255.255.255.0/24

192.168.1.4

255.255.255.54-255.255.255.62

8

255.255.255.0/24

192.168.1.5

255.255.255.63-255.255.255.71

8

255.255.255.0/24

192.168.1.6

255.255.255.72-255.255.255.80

8

255.255.255.0/24

192.168.1.7

255.255.255.81-255.255.255.89

8

255.255.255.0/24

192.168.1.8

255.255.255.90-255.255.255.98

for it to be completed. Hosts will be assigned IP addresses as follows: (fill in the table below)

Device

Interface

IP Address

Connects to

IP Address

1841

Serial 0/0/0

11.11.11.100

ISP Router

11.11.11.1

Fa 0/0

Wired hosts

Wired host Range:

____.____.____.____

To

____.____.____.____

Fa 0/1

Linksys Internet

Linksys

Internet

1841 Fa 0/1

LAN Gateway

Wireless Hosts

Wireless host Range:

____.____.____.____

To

____.____.____.____

Step 4: Consider other subnetting options

What if there were more than 30 hosts that needed to be supported on either the wired or wireless portion of the network. You could borrow fewer bits, which would create fewer subnets, but each one would support a greater number of hosts per subnet.

How many bits would be borrowed to create four subnets?

Jawaban =Ialah 2 buah bit yang akan dipinjam

How many bits would be left for hosts on each subnet?

Jawaban = 5 sampai 8 bits

What is the maximum number of hosts each subnet could support?

Jawaban = 30 host – 2broadcast = 28 host

What would the subnet mask be in dotted decimal and slash number (/#) format?

255.255.255.224 atau 255.255.255.224 / 27

If you start with the same 192.168.1.0 network as before and subnet it into four subnets, what would the subnet numbers be?

b. The Rough Design Notes diagram noted that the wireless subnet would have up to 30 PCs connecting. In pairs or in small groups, discuss whether or not that creates a situation in which IP addresses might get wasted. Does it matter, and why or why not?